Unhappily married individuals report poorer mental and physical health than either happily married or divorced people of the same race, sex, and age. This project, an intensive, longitudinal investigation of satisfied and dissatisfied newlyweds, will provide very valuable data on psychological and physiological mechanisms that are thought to lead to the observed health differences. A sample of 90 couples who have been married for six months will be recruited, half of whom are high in marital satisfaction, and half who are low; while newlyweds generally report high marital satisfaction, about 20% are already disenchanted in the first year, and these initial differences in marital satisfaction are associated with much greater differences two years later. Psychological data (behavioral and self-report) and physiological data (endocrine and immune function) will be obtained from the couples during a 24-hour admission to the Ohio State University Clinical Research Center (CRC), with the full assessment repeated two years later on the same couples. Immunological and self-report data will also be gathered in the one-year interval between CRC admissions, and health data will be collected every three months. The prospective design will provide important data on the relationships among psychological, endocrinological, and immunological changes related to changes in marital quality. The ubiquity of marital discord makes it a particularly important area for this multifaceted interdisciplinary research effort.